Description:

Chocolate Doom is a game engine that aims to accurately reproduce the experience
of playing vanilla Doom. It is a conservative, historically accurate Doom source
port, which is compatible with the thousands of mods and levels that were made
before the Doom source code was released. Rather than flashy new graphics,
Chocolate Doom's main features are its accurate reproduction of the game as it
was played in the 1990s.

The following games can be played:
-Doom (including the Ultimate Doom expansion pack)
-Doom II
-Final Doom
-Chex Quest

It is also possible to play these expansion packs and commercial games:
-The Master Levels for Doom II
-Hacx

And also various TCs and WAD files:
http://www.chocolate-doom.org/wiki/index.php/User_guide